Pruritus is a dermatological disorder that is characterized by an unpleasant, itchy sensation of the skin. Typically pruritus provokes scratching, which is sometimes severe enough to irritate and inflame the skin of afflicted patients, and can lead to infection. Unfortunately, pruritus afflicts a large population with the elderly being especially vulnerable to moderate to severe outbreaks of pruritus.
Pruritus is most commonly caused by other dermatological conditions such as dry skin, xerosis, atopic dermatitis, allergic contact dermatitis, bullous pemphigoid, dermatitis herpetiformis, seborrheic dermatitis, folliculitis, psoriasis, lichen planus, mycosis fungoides, sunburn, local infection, scabies, and pediculosis corporis. However, pruritus can also be a side effect from another systemic irregularity or disease, such as iron deficiency anemia, severe chronic renal failure, neurodermatitis, delusions of parasitosis, polycythemia rubra vera, Hodgkin's lymphoma, malignant carcinoid, multiple myeloma, scleroderma, rapid weight loss (e.g. anorexia nervosa), hyperthyroidism (e.g. Grave's disease), urticaria, cholestasis, systemic infection, HIV, filariasis, schistosomiasis, onchocerciasis, ascariasis, hookworm, trichinosis, and parvovirus B19.
Patients suffering from pruritus induced by another dermatological disorder can further exacerbate the condition of the disorder by excessively scratching the affected area in an attempt to alleviate the pruritus. Many times this leads to patients inadvertently spreading the dermatological disorder to uninfected areas unintentionally, and with only minimal relief of the pruritus.
Likewise, patients suffering from pruritus induced by a systemic irregularity condition can possibly worsen the condition by excessively scratching the affected area. Even more of a concern is that a patient suffering from systemic induced pruritus will excessively scratch the affected area so much that the excessive scratching will lead to irritation and possibly infection.
Previous treatments for patients suffering from pruritus required administering a topical steroid, such as a topical corticosteroid, stabilized in a cream or ointment to the affected area of the patient. The most common corticosteroid used in this regard is hydrocortisone. However, as with all steroidal treatments, topical corticosteroids cause undesirable side effects in the patients being treated. Typical side effects experienced by patients being treated with topical corticosteroids include burning, itching, irritation, dryness, infection, striae, telangiectasia, dark red spots, painful pus-filled blisters in hair follicles, thinning of the skin, and easy bruising and tearing of the skin on the areas being treated. These side effects can exasperate the pruritus experienced by the patient, and can lead the patient to continue scratching the affected area.
Besides exasperating the pruritus, continued scratching by the patient as a result of these unwanted side effects can further inflame other dermatological skin conditions being experienced by the patient, as well as lead to additional inflammation and possible infection of the affected area. Additionally, some patients experiencing pruritus cannot take topical corticosteroid treatments due to allergic reactions from the treatment.
Moreover, patients being treated with topical corticosteroids need to be monitored by physicians to ensure that heavy absorption of corticosteroids through the skin does not lead to adrenal gland suppression, excessive fluid retention, lethargy, raised blood pressure, and diabetes.
Traditionally, previous topical corticosteroid treatments for pruritus are stabilized in heavy creams or ointments that leave a greasy feeling on the skin after applied. Typical previous pruritic creams and ointments contain a high level of lipophilic agents such as fatty acids, fatty acid esters, fatty alcohols, mineral oil, and petrolatum. High levels of lipophilic agents are used to help stabilize the topical corticosteroid, which can degenerate rapidly in an unstable composition.
However, these lipophilic agents used to stabilize the corticosteroid can reduce the topical availability and efficiency of the topical corticosteroid by smothering the corticosteroid in a lipid covering, or envelope. This is especially true of previously known compositions, which contain high levels of lipophilic agents.
For example, U.S. Pat. No. 4,797,402 to Dorsey discloses a hydrophilic ointment comprising hydrocortisone, peppermint oil, urea, surfactant, solvent, and white petrolatum used for treating skin disorders such as eczema, dermatitis, rashes, cutaneous candidiasis, pruritus ani, pruritus vulvae, and lichen simplex chronicus. Dorsey discloses using an amount of petrolatum in the ointment base from 64.45% to 93.79% by weight.
Similarly, U.S. Pat. No. 5,061,700 to Dow, et al. discloses topical ointments comprising glyceryl acetate, an oleaginous material, and a corticosteroid to treat skin disorders. In particular, Dow, et al. discloses the oleaginous material can be from 30% to 99.75% by weight.
Thus, the lipophilic agent not only makes the previous compositions heavy and greasy, but also reduces the topical availability of the corticosteroid in the topical compositions, as well as reduces the efficiency of the composition.
Accordingly, topical anti-pruritic compositions for treating pruritus in a patient that provide a more effective treatment of pruritus in comparison to treatment of pruritus achieved by administration of a topical composition containing a corticosteroid were previously unknown in the art. Moreover, many of the previously known treatments for pruritus were creams or ointments comprising high levels of lipophilic agents, which retard the topical availability and efficiency of the topical corticosteroid. Thus, a topical anti-pruritic composition comprising a low amount of lipophilic agents, while maintaining the stability of the anti-pruritic agent and increasing the efficiency and topical availability of the anti-pruritic agent was previously unknown in the art.
For these reasons, there remains a need in the art for topical anti-pruritic compositions that are more effective in treating pruritus in comparison to previous treatments containing a corticosteroid. In this regard, there remains a particular need for topical compositions that treat pruritus quicker than do hydrocortisone-containing compositions. Additionally, there remains a need in the art for a topical anti-pruritic composition comprising a low amount of lipophilic agents, while maintaining the stability of the anti-pruritic agent and increasing the efficiency and topical availability of the anti-pruritic agent. The present subject matter addresses these needs.